Hydrocracking of hydrocarbons with the use of a catalyst comprising nickel metal and a heteropoly acid on alumina



United States Patent 3,156,641 HYDROCRACKING 0F HYDROCARBONS WITH THEUSE OF A CATALYST COMPRISING NICKEL METAL AND A HETEROPOLY AClD 0NALUMINA Herman S. Seelig, Forest Park, Valparaiso, Harry M. Brennan,Hammond, and Louis Charles Gutherlet, Cedar Lake, Ind, assignors toStandard Gil Company, Chicago, 1th, a corporation of Indiana No Drawing.Filed June 15, 1960, Ser. No. 36,177 16 Claims. (Cl. 208-112) Thisinvention relates to the catalytic conversion of hydrocarbons, and moreparticularly concerns the catalytic hydrocracking of hydrocarbons toobtain predominantly gasoline boiling range products.

Most of the modern day petroleum refineries are geared to the productionof maximum amounts of gasoline. To achieve this involves the utilizationof a variety of processes to convert loWer-than-gasoline andhigher-thangasoline boiling range hydrocarbons into fractions suitablefor inclusion into high octane gasoline products. While many successfulprocesses are available for accomplishing these conversions, nonethelessa number of high boiling feed stocks have effectively resistedcommercial exploitation as sources of gasoline. For example, cycle oilsfrom catalytic or thermal cracking processes, While often recycled forfurther cracking, are, in general, unattractive by reason of the highseverities which they require forconversion. Moreover, these refractorycycle oils usually give relatively low yields of usable gasoline.Accordingly, a major object of the present invention is to provide aprocess for converting hydrocarbons, especially the higher boiling andrefractory cycle oils, to products which predominantly boil in thegasoline boiling rangeroughly butanes through about 400 F.

Briefly, in accordance With the invention, it has now been discoveredthat high boiling hydrocarbons may be catalytically cracked andhydrogenated, or hydrocracked, to obtain predominantly gasoline boilingrange products of high octane number, by contacting the hydrocarbonswith hydrogen gas in the presence of a catalyst essentially comprisingnickel metal and heteropoly acid on alumina. When such contact iseffected at moderately low temperatures and high pressures, partialsaturation of polynuclear aromatics occurs, With subsequent cracking ofthe saturated portion into alkylbenzenes and isoparaiiins, both beingdesirable high octane number components of gasoline. In addition, normalparaflins contained in the hydrocarbon feed are apparently'cracked intoproducts having a higher than equilibrium concentration of isoparaffins.An unusual feature of the invention is that only a very small portion ofthe hydrocarbon feed stocks are converted into unusable dry gas.

Heteropoly acids refer to normally solid complex inorganic substances ofhigh molecular weight in which two or more different acid cations oroxides of metals or metalloids are associated with varying frequentlyindeterminate amounts of combined Water as Water of hydration, accordingto the definition given in Fleck US. Patent 2,547,380. Illustrative ofthe heteropoly acids are phosphot ungstic acid, silicotungstic acid,phosphomolyb: dic acid, phosphovanadic acid, phosphomolybdotungsticacid,"silicomolybdovanadic acid, titanomolybdotungstic acid,vanadomolybdic acid, borotungstic acid, germanemolybdic acid,chromiomolybdic acid, and the like. i The inventive catalyst compositionmay contain from about 0.1 to about 24 percent by Weight,total basis, ofnickel metal, and from about 1 to about 60 percent by weight ofheteropoly acid.

The alumina base or support advantageously comprises 4 ture, may behydrocracked successfully.

these allotropic forms. These definitions of alumina are the definitionsadopted as standard nomenclature by Russell in his brochure entitledAlumina Properties, Technical Paper No. 10, 1953, Aluminum Company ofAmerica, and by Stumpf et al., Ind. Eng. Chem., 42, 1950, pages1398-1403.

The invention in its Various aspects will be more fully described in theensuing subsections.

Feed Stocks A major advantage of the hydrocracking process is that itpermits a wide variety of hydrocarbon feed stocks to be converted topredominantly gasoline-boiling range products of high octane number. Thefeed stocks which may be satisfactorily hydrocracked may havecompositions ranging from essentially all saturates to essentially allaromatics. saturates, as noted earlier, are hydrocracked togasoline-boiling-range parafiins which containing ahigher-than-equilibrium concentration of isoparaftins in the product. Inthe case of polynuclear aromatic compounds these are partiallyhydrogenated to a tetrahydronaphthalene-type structure, and thehydrogenated ring portion is hydrocracked to afford an alkyl substitutedbenzene and an isoparaflin.

High boiling fractions of crude oil constitute exceedingly advantageousfeed stocks for the hydrocracking process. These fractions may rangefrom naphtha and kerosene through light and heavy virgin gas oils, tothe light and heavy vacuum gas oils and even to paraffin wax. Theindividual compositions of each fraction Will vary considerably inaccordance with crude oil source, and similarly the boiling ranges ofthe respective fractions will depend on fractionation conditions.Speaking very roughly, naphtha boils at about 200-400 F., kerosene has aboiling range of about 325-500 F., and the virgin gas oils may have aninitial boiling point of around 400 and a final boiling point of 700 F.and possibly higher. Vacuum gas oils are exceedingly high boiling. T eseVirgin stocks may be hydrocracked to high octane gasoline. Yields willbe significantly higher than can be obtained by conventional fluid bedcatalytic cracking.

Cycle oils and cycle oil extracts from catalytic cracking constitutemost valuable feed stocks. These cycle oils are the distillates boilinghigher than gasoline and are obtained as a product or byproduct ofcatalytic cracking. Cycle oils normally are enriched inpolynucleararomatics and the hydrocracked product will haveoutstandingly high octane numbers. A typical light catalytic cycle oilmay have a boiling range of about 400600 F. (ASTM method) while a heavycatalytic cycle oil may have a boiling range of roughly 600-800 F.

Analogous to the light and heavy catalytic cycle oils are the light andheavy cycle oils derived from thermal cracking, delayed coking, and thelike. These gas oils are also typically aromatic and olefinic in nature.Either the light fraction, or the heavy fraction, or both in admix- Ineach case, the products have somewhat lower octane number than thoseobtained by hydrocracking catalytic cycle oils of corresponding boilingranges, but the yieldand octane curves are significantly higher thanfrom fluid bed catalytic cracking of the same materials.

In the hydroforming of petroleum naphthas, say virgin naphthas chieflyboiling in the ZOO-400 F. range,with a platinum type catalyst (e.g.,platinum on eta or gamma Ti product is obtained. This polymer boilsabove around either gamma alumina or eta alumina, or mixtures of nucleararomatics. f had only limited utility as a high boiling solvent,"bu't by425 F. and consists almost entirely of alkylated naphthalenes with smallamounts of still higher boiling poly- This bottom fraction hasheretofore means of the present invention it may be converted inPatented Nov. 10, 1964 high yields to gasoline having an octane numberin excess of 100, research clear.

In the production of lubricant oils, a virgin distillate of suitableboiling range may be subjected to extraction by selective solvents suchas sulfur dioxide, Chlorex, phenol, or the like to remove an aromaticmaterial. This aromatic extract, either alone or in admixture with otherfeeds, is an ideal feed stock.

The inventive process is also valuable for the mild hydrocracking ofmaterials boiling in the gasoline boiling range to obtain products ofsimilar or only slightly lower boiling range of high octane number.Thus, light and heavy virgin gasoline, the raffinate remaining aftersolvent extraction of aromatics from a petroleum hydroformate, and otherchiefly saturated feed stocks may be processed according to theinvention.

Product yields are dependent upon many factors both with respect to feedstocks and hydrocracking conditions. Consequently, althoughgeneralizations may be developed, no detailed prediction or correlationof yields or octane numbers are possible Without involving awkwardinclusion of a multitude of variables. In general however, the higherthe aromatic content of the feed stock the higher will be product yield(gasoline boiling range materials) at any given product octane number.Other factors being equal, the higher the boiling range of feed stockthe greater is the gasoline boiling range product yield.

With any given feed stock, the amount of gasoline produced increases asthe severity of operation goes up. It is convenient to express severityin terms of percentage of feed converted to gasoline and other products,that is dry gas and coke. Conversion is then defined as 100 minus thepercentage of unconverted feed remaining in the product. Thus, 40%conversion on a once-through basis would mean that 60% of original feedstock remained, while 40% of the original feed stock (on a weight basis)was converted to gasoline and lower boiling products. In tests atseverities ranging from about 7% to over 95% conversion, the dry gasyield never exceeded about weight percent on feed, and with heavy gasoil feeds substantially all of the product boiling below 400 F.comprised high octane number gasoline.

Although the inventive catalyst composition is especially rugged andstable, it nonetheless is subject to poisoning by relatively minoramounts of non-hydrocarbon material that may be in the feed stock. Forthis reason, it is usually necessary to pretreat all feeds and removenon-hydrocarbon materials, unless by the nature of the previous historyof such feeds they have been freed of contaminants.

Sulfur apparently represents the most serious catalyst poisoning. Sulfurlevels much in excess of about 50 parts per million should be avoided ifsatisfactory catalyst life is to be achieved. If possible the sulfurlevel should be below about 10 parts per million, advantageously evenless than about 2 p.p.rn. Similarly, hydrogen sulfide in the hydrogengas supplied to the hydrocracking process should also be low; preferablyless than 0.01% at temperatures around 700 F. and, if possible, lessthan 0.0001% when operating at lower temperatures, e.g., 450 F. Hydrogensulfide may be removed from a hydrogen containing gas by scrubbing withcaustic, monoethanolamine, diethanolamine, or similar alkaline media,desirably followed by contact with a dehydrating agent such as ethyleneglycol, alumina, or'a molecular seive material.

Nitrogen and oxygen, as components of organic compounds, also appear tobe undesirable in a feed stock. Consequently, efforts should be made toreduce or eliminate these materials.

Process Conditions Conditions which are employed in hydro cracking maybe selected over a relatively wide range and are normally correlatedwith the nature of the feed stock to produce either a desired conversionor a desired octane number of product. In general, partial saturation ofpolynuclear aromatics to cycloalkyl aromatics and cracking of thesaturated ring portion thereof are favored by high pressures andmoderate temperatures, and an increase in either pressure or temperaturehas the eilect of increasing conversion levels. Excellent results forboth virgin and catalytically or thermally cracked feeds may be achievedat pressures in the range of about 500- 2,000 p.s.i.g. and temperaturesin the range of about 400-700 F., with optimum results occurring atpressures of about 1,0001,500 p.s.i.g. and temperatures of about 500600F. For highly refractory stocks, especially those containing lowermolecular weight parafiins or aromatics, the pressure may range up toabout 3,000 p.s.i.g. or even higher and similarly the temperature may beas high as 900 F. average catalyst temperature or higher. Where onlymild conversion per pass is desired, the pressure and/or temperature maybe lower than the ranges given above, and may be as little as 300p.s.i.g. or lower and 400 F. or lower, respectively.

The space velocity, expressed conventionally in terms of volumes of oilfeed stock per volume of catalyst per hour, may range from about 0.05 toabout 5.0, more suitably from about 0.1 to about 2.0, e.g., 0.2-0.5.Reducing the space velocity, or in other words decreasing the chargerate, increases conversion.

Hydrogen to oil ratio, expressed in terms of standard cubic feet ofhydrogen gas (60 F., 760 mm. pressure) per barrel of oil feed appears tobe a relatively insensitive variable. Major changes in hydrogen/oilratio do however exert a noticeable alteration of conversion and productquality, and accordingly it is generally desirable to maintain thisratio within the range of about l,000l0,000 s.c.f.b., advantageouslyabout 2,0005,000 s.c.f.b., e.g., 3,0004,000 s.c.f.b.

Naturally, the activity of nickel and heteropoly acid on aluminacatalyst is an important variable to be considered when determiningoptimum process conditions, and consequently this factor must be takeninto account in estimating or predicting yields and octane numbers.

It has been found however that over exceedingly wide ranges ofconditions, and in fact over all conditions experimentally investigated,the products chiefly boil within the gasoline boiling range. That is,more than 50% by weight of the feed stock which is converted to productsboiling below about 400 F. consists of hydrocarbons in the butane andheavier range. Only a minor portion of the product, generally much lessthan about 5% by weight, consists of methane-ethane-propanehydrocarbons. This product distribution is unique when considering thesubstantially higher dry gas (methaneethane-propane) yields from otherprocesses for cracking hydrocarbons such as thermal cracking, or fluidcatalytic cracking over a silica-alumina type catalyst.

Catalyst Preparation Numerous techniques are available for preparing thenickel and heteropoly acid on alumina catalyst. In brief, these methodsgenerally involve the preparation of a hydrous alumina which, uponsubsequent calcination, will provide either gamma or eta alumina ormixtures of the two. At some stage of alumina production, aheat-decomposable nickel compound and the heteropoly acid are added.Examples of heat decomposable nickel compounds, which decompose tonickel oxide on heating which may be reduced to nickel metal withhydrogen at elevated temperature, include nickel nitrate, nickel (H)acetate, nickel (H) carbonate, nickel formate, nickel (II, III)hydroxide, nickel oxalate, various hydrated forms of the foregoingcompounds, nickel carbonyl, dicyclopentadienyl nickel, and variousnickel clzelates such as the ethylene-diamine tetraacetic acid, asparticacid, glutainic acid, and the alanine chelates.

in the reaction.

The alumina base may be prepared by any of the methods known to the artfor obtaining the desirable form of alumina. For example, gamma aluminais converted by calcining alpha alumina monohydrate, which in turn isobtained by drying alpha alumina trihydrate. The trihydrate, or otherform of hydrous alumina ultimately yielding gamma alumina, may beobtained by such means as: reacting pure aluminum metal and water above250 F.; reacting aluminum metal with water containing a minor amount ofan acid such as dilute HCl; digesting aluminum metal amalgamated withmercury or a mercuric compound such as the oxide with water or withwater containing a dilute organic acid such as acetic acid; or byreacting aluminum metal with an aqueous strong acid. In each case, thehydrous alumina may be modified by adjusting the pH to within the rangeof about 6.8-7.8 with a base, preferably a nitrogen base such as ammoniaor ethanolarnine.

Alumina which contains at least a substantial proportion, e.g., 5% ormore ranging up to 95% or more, of the eta form may also be prepared byany of several well known means. Each of the following methods affords ahydrous alumina which, upon drying, transforms to beta aluminatrihydrate, and upon further heating or calcination passes through thealpha alumina monohydrate stage and yields eta alumina. By way ofexample, an alumina hydrosol or other form of hydrous alumina whichwould ordinarily be converted to gamma alumina may be aged at a pH inexcess of around 8 for from 1 to 48 or more hours, after which theresultant alumina may be dried and calcined to eta alumina. Othermethods of preparing eta alumina, or an alumina containing a substantialproportion of the eta phase, include: reacting water on finely dividedor amalgamated aluminum metal at a temperature below 104 F.; hydrolyzingan aluminum alkoxide at room temperature or below; alkalyzing an aqueoussolution of an acid-acting watersoluble aluminum salt such as thenitrate or chloride; acidification or neutralization of a basic aluminumsalt as sodium aluminate; or by hydrolyzing a neutral aluminum salt suchas aluminum acetate.

According to the preferred method of preparing the alumina support,whether gamma or eta, aluminum metal in the form of sheets, granules,turnings, shot, or other high surface area forms is subjected toamalgamation by contact with mercury or with an aqueous solution of amercuric salt. The amalgamated aluminum is then digested in water in thepresence of a low concentration (suitably about 0.5-7 percent by weight)of acetic acid or other weak organic carboxylic acid as a peptizingagent. The reaction goes forward readily at ordinarily or autogenouspressures and at temperatures above about 100 F., preferably about125-2l0 F. Thick viscous hydrosols are obtained at temperatures above160 F., while relatively thin hydrosols are obtained at temperaturesbelow 160 F. narily varies from about 2 to about 8% A1 0 The mixture ofamalgamated aluminum and acidulated water is preferably agitated inorder to improve the contact of the reacting materials and to assist inbreaking the layer of froth which is ordinarily formed by hydrogenliberated A reflux condenser is advantageously employed to condensewater and acid vapors from the emerging hydrogen stream and to returnthe resulting condensate to the reaction vessel. The reaction graduallyslows down after about 24 hours and ultimately ceases for all practicalpurposes after about 40 hours. The resultanthydrosol product'is a syrupyliquid of opalescent, nearly transparent appearance, and may be furtherclarified by settling, centrifugation, filtration, or the like to removeany suspended solids, including particles of metallic mercury. For gammaalumina, the hydrosol may be dried at ZOO-400 F. for 6-24- hours toafford alpha alumina trihydrate. Upon calcination at 800-1200 F. for 1-6hours the alpha trihydrate forms gamma alumina.

The alumina concentration ordi- The method described immediately abovemay alsobe employed, according to the preferred embodiment of thisinvention, to manufacture eta alumina. To obtain the eta modification,the hydrosol is agitated and commingled with an alkaline substance,preferably a nitrogen base such as ammonia, in a quantity sufiicient toraise the pH above about 8.5, but insutficient to convert anyconsiderable portion of the alumina into an aluminate salt. The pH isordinarily maintained below about 12, and preferably is in the range ofabout 10-11. The alkalized hydrosol is aged for about 1 to 48 hours ormore at about 50250 F., preferably around 70-100 F., for about 6 to 24hours, the shorter aging periods corresponding generally to the higherpH levels and (in lesser degree) to the higher temperatures. During thisoperation, White, finely divided hydrous alumina forms in the liquidphase as a filterable slurry. After completion of the desired alkaliaging the slurry may be filtered to separate the hydrous alumina,suitably at about ISO-200 F. in order to ensure rapid filtration rates.The filter cake is then dried at 400 F. to beta alumina trihydrate,i.e., to a water content less than about 50%, wet basis, preferablybetween 15 and 40%; it may be calcined at 800- 1200 F. to a materialwhich contains at least a substantial portion, i.e., 5% or more of etaalumina.

The heat decomposable nickel compound is advantageously incorporatedinto the alumina as an aqueuos solu tion of such compound, and similarlythe heteropoly acid may be incorporated. In particular circumstanceshowever it may be desirable to employ organic solvents for eachsubstance. Incorporation of either or both of the heat decomposablenickel compound and the heteropoly acid may illustratively take place bycogelling with an alumina sol or gel, either before or after alkaliaging; by impregnation onto a solid alumina; by addition to the hydrousalumina which forms upon alkali aging of a hydrosol; by impregnationonto dried or calcined alumina; or by impregnation onto calcined andpelleted alumina.

Once the alumina is formed, one or more finishing operations may beneeded to prepare the catalyst in a physical form suitable foremployment is a fixed, fluidized, or moving bed hydrocracking unit.These finishing operations depend not only on the previous method ofmaking the catalyst and on the type of processing for which it is to beused, but on the choice of fabricating procedures adapted to providecatalysts of desirable particle size and shape. Accordingly, judiciousselection of finishing operation, generally in accordance withconsiderations well known to the art, may be relied upon to provide thefinal catalyst. After drying an alumina hydrosol or hydrogel the productis ordinarily in the form of a solid cake. This cake vmay be comminutedas by grinding and the ground alumina may then be calcined. At thisstage, it may or may not havethe heteropoly acid and/ or the nickelincorporated therein. Where alumina is prepared by a precipitationtechnique, ordinarily no comminution is necessary.

.A comminuted alumina which has either been dried or calcined and whichhas already had the nickel and heteropoly acid incorporated therein maybe formed into suitable shapes by, for example, admixing with alubricant such as Sterotex (hydrogenated coconut oil) formed into shapedparticles such as pills, pellets, extrudates, and the like prior to thehigh temperature calcination. Alternatively, if a dried and crushedalumina has not yet been treated with either nickel or heteropoly acid,these materials may be added in solution form to wet the dried alumina,after which it may be redried and then formed into shapes, or elseextruded in moist form and subsequently redried and calcined. Anothervariation is to extrude an alumina hydrosol, preferably a thickerhydrosol, into a bath of hot oil to form the alumina into beadlikespheres; the hot oil effects partial drying and solidifil cation, andmay be employed either with pure alumina or with alumina containingeither or both of the metal and heteropoly acid constituent.

After the nickel and heteropoly acid on alumina has been formed intosuitable shapes and calcined at a temperature of from about 800 to about1,200 F. (or up to the onset of alpha alumina transition) it ispreferable to reduce the catalyst in hydrogen prior to employment in ahydrocracking process. Reduction effects conversion of nickel oxide,resulting from decomposition of the heat decomposable nickel compoundduring calcination, to nickel metal. Reduction is best effected in astream of flowing hydrogen gas at atmospheric pressure until about atleast the stoichiometric requirement for converting nickel oxide to themetal has been met. Temperature for hydrogen reduction areadvantageously in the range of about 500900 F., preferably from about600 to about 800 F. The hydrogen flow rate, in units of standard cubicfeet per hour per ton of catalyst, is advantageously in the range ofabout 30 to 150, preferably from about 30 to 90. Efficient reductionconditions include a temperature of about 700750 F. and a hydrogen gasfiow rate of about 50-70 standard cubic feet per hour per ton ofcatalyst. Hydrogen reduction may take place shortly after calcination,or may be reserved until the calcined catalyst is placed in thehydrocracking reactor and before any processin. of hydrocarbons occurs.This latter procedure is most advantageous as it avoids problemsassociated with the pyrophoricity of catalysts containing finely dividednickel.

The final catalyst will advantageously contain from about 0.1 to about24 weight percent nickel metal and from about 1 to about 60 weightpercent heteropoly acid, the balance being essentially alumina. Thepreferred catalyst contains from about to about 30% heteropoly acid andfrom about 1 to about weight percent nickel metal, all figures being ontotal basis.

By way of illustration, but not by way of limitation, the followingspecific embodiments showing the preparation and use of the inventivecatalyst are furnished.

Example I In this example a nickel and silicotungstic acid on aluminacatalyst is prepared by impregnation of nickel and silicotungstic acidon a calcined Heard-type hydrosol to obtain gamma alumina as thesupport.

The alumina hydrosol is prepared by reacting amalgamated aluminum with2% aqueous acetic acid at 160 170 F. for 24 hours, at the end of whichtime the reaction subsides and the reaction product is allowed to settlefor 12 hours and the hydrosol decanted from the reaction vessel. Thehydrosol contains 5.51 weight percent alumina (Water free basis) and istreated with 10% aqueous ammonia to a pH of about 66.5 and then dried at255 F. and calcined for 3 hours at 900 F The resultant gamma alumina isground to 20-48 mesh.

To 35 grams of the ground gamma alumina is added a solution consistingof 32 grams silicotungstic acid and 40 cc. distilled water. The materialis allowed to soak with occasional mixing for one hour and then dried inair at 400 F. The dried material is calcined at 1100 F. for 4 hours.

The calcined material is then mixed with 40 cc. of a nickel acetatesolution having a nickel concentration of 0.9 mol per liter. Aftersoaking with occasional mixing for one hour, the catalyst is dried at400 F. and calcined at 1100 F. for 4 hours.

The catalyst is tested for its hydrocracking properties by employing thecatalyst to hydrocrack a light catalytic cycle oil, boiling within therange of about 420620 F.

and containing 3 parts per million sulfur, at 1000 p.s.i.g., 650 F aliquid hourly space velocity of 1.0, and 7000 standard cubic feet ofhydrogen per barrel of oil.

The test procedure involves reduction of cc. of catalyst in situ withhydrogen at 750 F. and atmospheric pressure for minutes. Oil is thenprocessed under the above test conditions for 3 hours before samples aretaken. Two consecutive one hour samples are then collected, and theliquid product is analyzed for C -C paraffins by gas chromatography.

The fourth hour sample produces 48.6 weight percent of C -C paraffins,and the fifth hour sample contains 44.3 weight percent paraffins. Bycomparison, a catalyst containing only 5% nickel on gamma alumina,without heteropoly acid, and prepared according to the same procedureproduces no detectable yield of C C parafiins.

Example 11 In this example the procedure is identical with that employedfor preparing and testing the catalyst in Example I, except that thequantity of silicotungstic acid is reduced to 8 grams. C -C parafiinsyields are 16.5 and 14.3 weight percent for the fourth and fifth hourruns.

Example III In this example, nickel and silicotungstic acid areimpregnated onto one-eighth inch diameter pellets of gamma alumina, andthe resultant catalyst is tested for hydrocracking activity.

Ground and calcined gamma alumina, prepared as in the manner of ExampleI, is mixed with 2% Sterotex, pelleted, and calcined for 4 hours at 1100F.

To 200 grams of the pelleted gamma alumina is added 200 cc. of asolution containing grams of silicotungstic acid in distilled water. Thepellets are allowed to soak with occasional stirring for one hour andthen dried at 400 F. and calcined at 1100 F. for 4 hours. This calcinedmaterial is then impregnated with cc. of a nickel acetate solutioncontaining 0.9 mol per liter of nickel. After soaking for one hour, withoccasional stirring, the catalyst is dried at 400 F. and calcined at1100 F. for 4 hours.

The test conditions are 1000 p.s.i.g., about 565 F. average catalysttemperature, 0.25 liquid hourly space velocity, and 3900 s.c.f.b. ofhydrogen. The catalyst is reduced with hydrogen for 4 hours at 750 F.and atmospheric pressure prior to introduction of the light catalyticcycle oil feed.

Oil is passed over the catalyst for 6 hours, the product of the lastfive hours being collected for analysis.

Essentially 100% of the catalytic cycle oil is converted to gasoline andlower boiling products. The methane yield is 0.04 weight percent ofproduct, ethane is 0.27, propane is 4.95, isobutane is 17.40, normalbutane is 5.13, pentane-l80 F. is 31.02 weight percent of product, andl80-400 F. is 41.18 weight percent.

Example IV A portion of the filter cake weighing 35 grams is commingledwith a solution consisting of 32 grams of silico tungstic acid and 40cc. of distilled water and the entire mixture is dried at 250 F. Thedried material is calcined for 3 hours at 900 F., and then ground toabout 30 mesh.

The calcined material is then mixed with 40 cc. of a nickel acetatesolution having a nickel concentration of 0.9 mol per liter. Aftersoaking with occasional mixing for one hour, the catalyst is dried at400 F and calcined at 1100 F. for 4 hours.

Example V In this example a Heard-type hydrosol is cogelled with bothnickel acetate and silicotungstic acid to produce a catalyst wherein thesupport is gamma alumina.

To a hydrosol containing 5.51% by weight of A1 and prepared as inExample I, a 65 weight percent aqueous silicotungstic acid solution anda 0.9 molar aqueous nickel acetate solution are simultaneously added inquantities sufficient to produce a final catalyst composition containing2% nickel and 10% silicotungstic acid. Cogelling occurs rapidly, and theresultant slurry is dried on a hot plate at about 250 F. for 4 hours.The dried material is calcined for 3 hours at 900 F., ground, mixed with2% Sterotex, pelleted, and recalcined for 4 hours at 1100 F.

Example VI In this example a nickel and phosphotungstic acid on gammaalumina is prepared, following the exact procedure set forth for ExampleI except that 32 grams of phosphotungstic acid is used.

Upon testing according to the procedure of Example I, the fourth andfifth hour samples indicate that 48.7 and 41.8 weight percent,respectively, product is C -C paraffins.

Example VII In this example a nickel and phosphotungstic acid on gammaalumina catalyst is prepared in precisely the manner described forExample II, except that 8 grams of phosphotung-stic acid is employed.

The fourth and fifth hour product samples contain 20.6 and 14.2 weightpercent C -C6 paralfins, respectively.

Example VIII In this example the procedure and catalyst of Example IIIare employed, except that the space velocity is increased to 1.0 and thetemperature raised to 630 F. Under these conditions, weight percentconversion is 85. The C -18O F. fraction, representing 27.8% on product,has an octane number, research method with 3 cc. TEL per gallon, of96.7. Heavy naphtha having a 180-400 F. boiling range and recovered in a40.6 weight percent yield on product has an octane number research plus3 cc. of 87 .8.

While the invention has been described with reference to certainspecific embodiments thereof, it is to be understood that these areillustrative only and not by way of limitation. Numerous modificationsand equivalents of our invention will be apparent from the foregoingdescription to those skilled in the art.

We claim:

1. A process for hydrocracking substantially sulfur-free hydrocarbons toobtain predominantly gasoline-boilingrange products of high octanenumber, said process being characterized by the conversion of apolynuclezar aromatic compounds to an alkyl-substituted benzene and anisoparafiin, which comprises contacting said hydrocarbons with hydrogengas under hydrocracking conditions in the presence of a catalystessentially comprising nickel metal and a heterop oly acid on alumina.

2. Process of claim 1 wherein said hydrocarbons are virgin gas oil.

'3. Process of claim 1 wherein said hydrocarbons are catalytic cycleoil.

4. Process of claim 1 wherein said heteropoly acid is phosphotungsticacid.

5. Process of claim 1 wherein said heteropoly acid is silicotungsticacid.

6. Process of claim 1 wherein said alumina is chiefly gamma alumina.

7. Process of claim 1 wherein said alumina is chiefly eta alumina.

8. Process of claim 1 wherein said hydrocracking conditions include apressure in the range of about 500-3000 p.s.i.g., a temperature in therange of about 400900 F a hydrogen to hydrocarbon ratio in the range ofabout LOGO-10,000 s.c. f.b., and a liquid hourly space velocity in therange of about 0.05 to about 5.0. 9. Process of claim 1 wherein saidhydrocracking conditions include a pressure in the range of aboutSOD-2,000 p.s.i.g., a temperature in the range of about 400-700 F., ahydrogen to hydrocarbon ratio in the range of about 2,0005,000 s.c.f.b.,and a liquid hourly space Velocity in the range of about 0.1-2.

10. Process of claim 1 wherein said catalyst essentially comprises fromabout 0.1 to about 24 weight percent nickel metal, for about 1-60 weightpercent heteropoly acid, the balance essentially comprising alumina.

11. A catalyst composition suitable for hydrocracking substantiallysulfur-free hydrocarbons to obtain predominantly gasoline-b oiling-rangeproducts of high octane number, which essentially comprises nickel metaland a heteropoly acid on alumina.

12. Composition of claim 11 wherein said heteropoly acid isphosphotungstic acid.

13. Composition of claim 11 wherein said heteropoly acid issilicotungstic acid.

14. Composition of claim 11 wherein said alumina is chiefly gammaalumina.

15. Composition of claim 11 wherein said alumina contains at least asubstantial proportion of eta alumina.

16. Composition of claim 11 wherein said catalyst essentially comprisesiirom about 0.1 to about 24 weight percent nickel metal and trom about 1to weight percent heteropoly acid, the balance essentially comprisingalumina.

References Cited in the file of this patent UNITED STATES PATENTS2,547,380 Fleck Apr. 3, 1951 2,554,597 Starnes et al May 29, 19512,744,052 Nozaki May 1, 1956 2,897,135 Doumani July 28, 1959 2,944,961McAfee July 1-2, 1960 2,953,515 Lanning Sept. 20,1960 2,958,651Kirshenbaum et a1. Nov. 1, 1960

1. A PROCESS FOR HYDROCRACKING SUBSTANTILLY SULFUR-FREE HYDROCARBONS TO OBTAIN PREDOMINANTLY GASOLINE-BOILINGRANGE PRODUCTS OF HIGH OCTANE NUMBER, SAID PROCESS BEING CHARACTERIZED BY THE CONVERSION OF A POLYNUCLEAR AROMATIC COMPOUNDS TO AN ALKYL-SUBSTITUTED BENZENE AND AN ISOPARAFFIN, WHICH COMPRISES CONTACTING SAID HYDROCARBONS WITH HYDROGEN GAS UNDER HYDROCRACKING CONDITIONS IN THE PRESENCE OF A CATALYST ESSENTIALLY COMPRISING NICKEL METAL AND A HETEROPOLY ACID ON ALUMINA. 